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Which Connection Is Best?
So which connection is best? It depends!
Generally, the answer depends on whether you already have a GPS or not. If you already have a GPS unit and nothing is wrong with it, you can stick with whatever connection your unit supports. If you don’t have a serial port, use a USB-to-serial converter to obtain the necessary serial port for connecting. If you have a GPS that can connect to a USB port, make use of that. Be careful not to damage the connector, however, as I’ve found that they can be more delicate than serial port connectors.
If you are buying a new GPS, the main connection-related question that should influence your decision is whether to opt for a wired connection or a wireless connection. If you have a PC, laptop, or PDA that is or can be made Bluetooth-compatible easily (it can be quite costly for some PDAs), then a wireless connection might be your best bet.
However, remember that if you choose wireless, you will need both a GPS receiver and a data processor (such as your laptop or PDA) with you at all times. That’s twice as many devices to take care of and protect from the elements and twice as many devices needing a power supply.
Generally, wireless devices make far better second GPS receivers for those already using GPS than they do GPS receivers for the first-time GPS owner.
Troubleshooting Problems
This section examines the connection problems that you might encounter when connecting your GPS receiver to another device. Fortunately, problems are few and far between, but some can be especially annoying and hard to fix.
PC Connection Trouble
The main problem that users encounter when connecting their GPS to a PC or other device is that they just can’t get the two devices to communicate.
Here are some things to check if you can’t get the GPS and device to communicate through a cable connection:
1.Check the cable connectors for damage. In fact, check the whole cable for any visible signs of damage. If it’s a cable that you made, ensure that the connectors are sound — open them up if you suspect that there might be a problem. If you can, try the connection with a different cable. This way, you can isolate whether it is a cable problem or a settings issue on either the GPS or the PC/PDA.
2.Check the connections. If the cable seems okay, check the connections at both the GPS and the device. Undo and redo the connections and retry the connection.
3.Check the batteries on the GPS receiver. Low batteries can cause problems. Replace the batteries with known good batteries or newly recharged batteries. If possible, power the device externally.
156 Part II — Software Hacks
4.Try different software. If you are having problems communicating with a particular software package, try a different software package if you have one installed. When trying different software, follow these steps carefully:
a.Close the software involved.
b.Switch off the GPS.
c.Shut down the PC.
d.After the PC is shut down, switch the GPS on and allow it to fully power on before switching on the PC.
e.Switch the PC on and allow it to fully load.
f.Start the software (or another GPS-capable software application) again.
5.Check connection type and speed. Many software packages can be set to a variety of communication protocols and speeds (see Figure 7-9). If you have any doubts as to how to do this, consult the software manufacturer’s website. The same goes for GPS units themselves (see Figure 7-10). Garmin units can be set to either the Garmin proprietary format or the more generic NMEA protocol. Make sure that both the GPS and software are set to the same protocol and data transfer speed. For NMEA, try speeds of 4800 or 9600 bps.
FIGURE 7-9: Port speed settings on software
6.Check the serial port with another device. This can be handy when you are having problems.
7.Try a different serial port. Another option available is to try it on a different PC if you can. This helps you isolate hardware issues.
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FIGURE 7-10: Port speed settings on the Garmin eTrex
General PDA Connection Trouble
Connecting a GPS to a PDA can be just as prone to a dead connection as can a PC-to-GPS connection. Here is the procedure for isolating and fixing a problem:
1.Check the cable connectors. Check the entire cable, including the connectors, for damage. Cables used outdoors can be subjected to damage (stretching being particularly bad for them). Check the connectors carefully for dirt or damage — dirt in the connectors can cause terrible damage to your devices, and you should take steps to protect them from the elements.
2.Check the connections. If the cable seems okay, check the connections at both the GPS and the device. Undo and redo the connections and retry the connection. Connections at the bottom of iPAQ devices are particularly prone to damage and great care needs to be taken with them. Never yank the cable from the base of a PDA and never force a connector in place — if things don’t seem right, take a closer look in case you damage something further.
Damaging the connector at the base of an iPAQ can result in a very expensive repair, as the whole motherboard will need replacing!
3.Check batteries. Low batteries can cause problems. Replace batteries with known good batteries or newly recharged batteries. If possible, power the device externally. Try the connection a second time, this time following these instructions:
a.Switch off the GPS.
b.Switch off the PDA.
c.Disconnect the cable fully.
d.Reattach the cable to the GPS and the PDA.
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e.Switch on the GPS and allow it to acquire a satellite lock.
f.Soft reset the PDA (consult your manual for details as to how to do that), switch the PDA on, and run the software.
g.See if you get a connection.
4.Check connection type and speed. As with their PC counterparts, many software packages designed for GPS use on PDAs can be set to a variety of communication protocols and speeds (see Figure 7-11). Garmin units can be set to either the Garmin proprietary format or the more generic NMEA protocol. If you have a Garmin GPS, I normally find that the connection is more stable if the Garmin protocol is used. Make sure both the GPS and software are set to the same protocol and data transfer speed. For NMEA, try speeds of 4800 or 9600 bps.
FIGURE 7-11: Pocket PC software is similar to most desktop PC software in that it will have port settings information.
General Bluetooth Connection Trouble
Bluetooth connections can sometimes be problematic to set up. Here is a guide to help you with these kinds of connections:
1.Make sure that both devices are Bluetooth-compliant. This seems obvious, but it is sometimes hard to determine which PDAs are Bluetooth-compliant.
2.Switch off all other Bluetooth devices in the vicinity.
3.Make sure that the GPS and the PDA/PC are close together and that no walls are obscuring the signal. Bring the two devices to within 1 meter of each other while troubleshooting problems.